"I received a notification from a name I didn't know," she said.
"It's not okay. Not my child, she's all I have. India is my heart, that's not right. We're already on edge, so why would you do that?"
The photo's privacy setting had been set to 'Public' since it was posted two years ago, which explains how a stranger would be able to leave a comment without being Facebook friends with the owner.
Now, Ms Williams is terrified that he may act on his threat. Before news broke of his termination from the police force, she said: "Let's say he does lose his job. How do I know he won't come and retaliate? How do I know that? I don't."
She also said she plans to "protect" her daughter from being afraid of all police as a result of the incident.
"Maybe I'll just say he was one bad cop. Not all of them are like that. I don't think she'll think they're all like that either way. She loves police."
Francis Donchez Jr., the police chief in Overland Park, personally called Ms Williams to apologise for the incident.
Officers initially questioned whether Wilson's account had been hacked, but they later in the day came to the conclusion that he had posted the threatening remark.
This is the statement released by Overland Park Police Department on Facebook, the morning after the incident took place.